By Dovydas Kersys · Chapter 18 of 58 in Machine Commissioning.

Before you begin: Follow the machine documentation, risk assessment, site procedures and lockout/tagout requirements. Commissioning can expose personnel to electrical energy, stored pressure and unexpected motion. Never defeat a safety function merely to make a test easier. Examples and diagrams are generic and must be checked against the actual machine.

Good commissioning includes the software layer that maintenance will later rely on. Tag names, descriptions, engineering units, channel diagnostics and HMI labels should match the real machine.

Why this matters during commissioning

A correct wire connected to a poorly named tag still creates future troubleshooting risk. Commissioning is the opportunity to make the system understandable.

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Commissioning procedure

  1. Compare I/O list, PLC tags, electrical drawings and field labels.
  2. Standardize normally open/closed meaning in tag comments or logic.
  3. Check engineering units and scaling constants.
  4. Enable useful module diagnostics and map them into alarms where appropriate.
  5. Document spare channels and intentionally unused I/O.

Common failure patterns

  • Copy/paste tag descriptions from another station.
  • HMI label differs from panel/device label.
  • Spare input left with a misleading active alarm.
  • Diagnostic bits exist but are never shown to technicians.

Evidence to record

  • Tag/address mapping
  • Description/units
  • Normal state
  • Diagnostic behavior
  • Documentation update

FIELD RULE: A well-commissioned machine tells the technician what is wrong instead of only stopping.

Continue the series

Adapted from Machine Commissioning for Maintenance and Automation Technicians, by Dovydas Kersys. © 2026 Dovydas Kersys. Featured cover image is an AI-generated editorial illustration.

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